DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed high- or intermediate-grade* malignant soft tissue sarcoma, including any of the following subtypes:

  • Fibroblastic tumor (e.g., adult fibrosarcoma, myxofibrosarcoma, sclerosing epithelioid fibrosarcoma, and malignant solitary fibrous tumors)
  • Fibrohistiocytic tumor (e.g., pleomorphic malignant fibrous histiocytoma [MFH], giant cell MFH, and inflammatory MFH)
  • Leiomyosarcoma
  • Malignant glomus tumors
  • Skeletal muscle tumors (e.g., pleomorphic and alveolar rhabdomyosarcoma)
  • Vascular tumor (e.g., epithelioid hemangioendothelioma, and angiosarcoma)
  • Uncertain differentiation (e.g., synovial, epithelioid, alveolar soft part, clear cell, desmoplastic small round cell, extra-renal rhabdoid, malignant mesenchymoma, perivascular epithelioid cell tumor [PEComa], intimal sarcoma)
  • Malignant peripheral nerve sheath tumors
  • Undifferentiated soft tissue sarcomas not otherwise specified
  • Other types of sarcoma, if approved by the medical monitors NOTE: *Low-grade tumors are allowed provided there is disease progression.

• Measurable disease

  • New lesions occurring in previously irradiated field are considered measurable
  • No previously irradiated lesions only disease

• Disease progression by RECIST confirmed by radiological evaluation when compared to a disease assessment done within the past 6 months

  • Assessment may be done within the past 12 months in patients who had only received prior systemic neoadjuvant or adjuvant therapy

• No more than 4 lines* of prior systemic therapy for advanced disease and meeting the following criteria:

  • No more than 2 of the lines should have been combination regimens
  • Disease has progressed on or after anthracycline-based regimen OR patients intolerant to the therapy
  • Disease has progressed on or after available standard chemotherapies unless medically contraindicated, therapy refused by patient, or patients intolerant to the therapy NOTE: *Neoadjuvant, adjuvant, and maintenance treatments are not counted for this criterion.

• Metastatic disease

  • No locally advanced disease only
  • No known history of CNS metastases or leptomeningeal tumor spread
  • No known intraluminal metastatic lesions with risk of bleeding
  • No endobronchial lesions and/or lesions infiltrating major pulmonary vessels

• The following tumor types are not allowed:

  • Adipocytic sarcomas (all types)
  • All rhabdomyosarcomas that are not alveolar or pleomorphic
  • Chondrosarcoma
  • Osteosarcoma
  • Ewing tumors and primitive neuroectodermal tumors
  • Gastrointestinal stromal tumors
  • Dermofibromatosis sarcoma protuberans
  • Inflammatory myofibroblastic sarcoma
  • Malignant mesothelioma
  • Mixed mesodermal tumors of the uterus
• Formalin-fixed paraffin-embedded tumor blocks and/or representative hematoxylin/eosin slides (preferably both) must be available

PATIENT CHARACTERISTICS:

• ANC ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• Hemoglobin ≥ 9 g/dL
• Prothrombin time ≤ 1.2 times upper limit of normal (ULN)
• Partial thromboplastin time OR INR ≤ 1.2 times ULN
• Bilirubin ≤ 1.5 times ULN
• AST and ALT ≤ 2.5 times ULN
• Serum creatinine ≤ 1.5 mg/dL OR creatinine clearance ≥ 50 mL/min
• Urine protein-creatinine ration (mg/dL) ≤ 1 OR 24-hour protein ≤ 150 mg
• Not pregnant
• Not nursing during study and for at least 14 days after completion of study treatment
• Negative pregnancy test
• Fertile patients must use effective contraception
• No other prior malignancies within the past 3 years except for basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix or breast
• Able to swallow and retain oral medication
• No other malignancy within the past 3 years except basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix or breast
• Toxicity from prior therapy has resolved to ≤ grade 1 (except alopecia) and is not progressing in severity

• Cardiac function clinically normal by 12 lead ECG and no history of any cardiovascular conditions within the past 6 months including any of the following:

  • Myocardial infarction
  • Unstable angina
  • Symptomatic peripheral vascular disease
  • NYHA class III-IV congestive heart failure
• No prolongation of QTc interval > 480 msecs by 12-lead ECG
• LVEF normal by MUGA or ECHO

• No poorly controlled hypertension (i.e., BP > 150/90 mm Hg)

  • Initiation or adjustment of antihypertensive medication is permitted prior to study entry and BP must be reassessed twice separated by ≥ 1 hour resulting in ≤ 150/90 mm Hg

• Any of the following conditions are not allowed:

  • Prior cerebrovascular accident
  • Transient ischemic attack in the past 6 months

  • Deep venous thrombosis (DVT) or a pulmonary embolism in the past 6 months

    • Recent DVT treated with therapeutic anti-coagulating agents and remaining stable for at least 6 weeks allowed

• No history of clinically significant gastrointestinal disorders including any of the following:

  • Malabsorption syndrome
  • Active peptic ulcer disease
  • Inflammatory bowel disease
  • Ulcerative colitis
  • Gastrointestinal conditions with increased risk of perforation
  • Abdominal fistula within the past 28 days
  • Gastrointestinal perforation within the past 28 days
  • Intra-abdominal abscess within the past 28 days
• No evidence of active bleeding or bleeding diathesis

• No hemoptysis within the past 6 weeks

  • Any patient with prior hemoptysis associated with metastatic disease must have endobronchial lesions ruled out by bronchoscopy
• No major trauma within the past 28 days
• No presence of any non-healing wound, fracture, or ulcer
• No psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
• No known immediate or delayed hypersensitivity reaction or idiosyncrasy to drugs chemically related to pazopanib hydrochloride

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No cardiac angioplasty, stenting, or coronary artery bypass graft surgery within the past 6 months
• More than 6 months since prior and no concurrent amiodarone
• No major surgery within the past 28 days
• More than 14 days since prior and no concurrent other anticancer therapy, including chemotherapy, immunotherapy, biologic therapy, radiotherapy, targeted agents, investigational therapy, or hormonal therapy

• More than 14 days since prior and no concurrent substrates for the CYP450 enzymes, including any of the following:

  • Oral hypoglycemics (tolbutamide, chlorpropamide)
  • Ergot derivatives (dihydroergotamine, ergonovine, ergotamine, methylergonovine)
  • Neuroleptics (pimozide)
  • Antiarrhythmics (bepridil, flecainide, lidocaine, mexiletin, guanidine, propafenone)
  • Immune modulators (cyclosporine, tacrolimus, sirolimus)
  • Miscellaneous (theophylline, quetiapine, risperidone, tacrine, clozapine, atomoxetine)

• No prior inhibitors of angiogenesis and/or VEGF- or VEGFR-targeting agents

  • mTOR inhibitors are not considered angiogenesis inhibitors
• No major resection of the stomach or small bowel that could affect the absorption of study drug
• No concurrent therapy with any specifically prohibited medication or requirement for using any of these medications during treatment with pazopanib hydrochloride
• No concurrent hormone replacement therapy